May the segment division (description between differently classified segments) of a wild and scenic river be amended when such description is included in Section 3(a)?*

(*For some rivers, Congress has directed the river-administering agency in Section 3(b) to determine which classes “best fit the river or its various segments.”  These administratively segmented rivers should reflect on-the-ground circumstances and, therefore, are unlikely to require subsequent amendment.)

Yes. In a very few cases, the legislation designating a river erroneously describes a segment division and needs to be amended to fit on-the-ground circumstances. For example, the designating language for the Upper Rogue Wild & Scenic River unintentionally included a road and bridge crossing in a wild river corridor. In actuality, the classification division should have been above the bridge, affecting the length of the wild section by two-tenths of a mile. This situation requires the river administrator, through its respective department, to recommend an amendment of the Wild & Scenic Rivers Act (i.e., to recommend changing the description of a river’s segment division in Section 3(a) of the Wild & Scenic Rivers Act).

A proposal to amend a segment division must be carefully considered so as not to change the intent of Congress. Such consideration should include review of the legislative history, including any maps developed in the study process or as a part of the legislation, and full disclosure through a public process prior to recommending the amendment to Congress.

Source
Interagency Wild & Scenic Rivers Council